It is an object of the present invention to directionally discriminate penetrating charged particles (also called ionizing radiation), such as muons, electrons, positrons, protons, nuclei and ions. Existing methods in the prior art that achieve this object can be divided into two types:                1) Change-of-state chambers combined with a photoelectric effect, whereby the detection medium in devices such as the cloud chamber (Charles Wilson, 1936 Nobel Prize in Physics) and the bubble chamber (Donald Glaser, 1962 Nobel Prize in Physics) undergoes a change of state along the localized path of a penetrating charged particle. In the cloud chamber, the change of state in the detection medium is from vapor to liquid, whereas in the bubble chamber it is from liquid to vapor. These condensation paths are recorded photographically. Such devices were used in many basic particle physics discoveries in the early-mid 20th century, such as the discovery of the muon.        
For many decades, photographic methods were a primary tool of particle physicists.
Change-of-state chambers are used infrequently in modern science and industry in part because of the large uncertainty in response time due to the stochastic nature of molecular condensation/vaporization, and in part because of the precise temperature and pressure requirements of the reaction chambers. For most applications, such devices have been outclassed by the second existing method for the task at hand, namely:                2) The coincidence method (Walter Bothe, 1954 Nobel Prize in Physics), in which the temporal coincidence of multiple detectors, combined with the known spatial relationship of the detectors, is used to reconstruct a particle path. The more numerous, densely packed and fast-response the detectors, the more directional discrimination a coincidence array can achieve, in principle. The coincidence method is a fundamental tool in experimental physics and enjoys a near-monopoly of this task in science and industry, largely due to the method's affinity with digital electronics.        
In the coincidence method, a time window is chosen for two given detectors. If a particle is detected in one detector, a timer is started (the time window is opened). If the other detector produces a detection within that time window (before the timer runs out), then a coincidence output signal is produced. The speed of the particle and the spatial relationship between the two detectors serve to ‘set’ the minimum time window for a coincidence event caused by a single particle passing through both detectors.
There is a diverse field of detector types used in the employ of the coincidence method, from transparent scintillation or Cherenkov volumes optically coupled to one of any number of photodetectors, to spark chambers, to wire chambers, resistive plate chambers, drift chambers, Geiger-Muller tubes (the first historical application of the coincidence method), and others. A seminal coincidence method patent is U.S. Pat. No. 3,140,394 A, issued to Arthur Roberts in 1964. The one common trait in all of these devices is that the directional measurement arises from the temporal relationship of two or more signals originating from two or more detectors. This is a fundamental limitation and function of the coincidence method: it requires at least two detectors, firing in near-synchrony.
Therefore, the first disadvantage to note about the coincidence method is that a single detector of any existing type will not produce a directional discrimination: two or more detectors are always required in the coincidence method.
The second disadvantage of the coincidence method is that some method or means for the comparison of the timing of the two signals is required, such as Rossi's seminal circuit (1945). This can be costly, especially if very fine directional resolution is sought (requiring very fast detectors).
The third, more persistent, disadvantage of the coincidence method is that the method is prone to experiencing false positive signals caused by two or more particles impinging detectors within the temporal-coincidence time-window and thus mimicking the particle track of a single particle. These false positive signals are called accidental coincidences and can create significant noise or eclipse single-particle signal altogether.
Accidental coincidences are the nemesis of the coincidence method and require that the readout of the detectors be fast enough (have a small enough time resolution) to discriminate between a single-particle event (a true coincidence) and a two-or-more-particle event (an accidental coincidence). The ambient particle flux of the operating environment is therefore a primary concern for the coincidence method.
Because penetrating ionizing radiation is pervasive on Earth (from cosmic ray air showers and terrestrial radiation), and because these particles travel at relativistic speeds, coincidence detectors have to be fast to be reliable. This means that the detectors require nanosecond resolution or better for meter-scale coincidence arrays. This brings costs and other disadvantages to the coincidence method.
The need to outrun accidental coincidences has been a major driver of the development of ever-faster-response particle-detectors and photo-detectors, for use in coincidence arrays of many kinds. As compared to slow-response detectors, the faster-response detectors used in the coincidence method have the following general disadvantages:                a) Fast-response detectors are more expensive than slow-response detectors. Consider the cost of a (fast) PMT versus an equivalent detecting area of one or more (slow) photodiodes or CCDs. Slower-response detectors will remain less expensive than faster-response detectors for the foreseeable future, even as faster detector technologies develop.        b) Fast-response detectors require fast data acquisition, which is costlier than the slow data acquisition required by slow-response detectors.        c) Fast-response detectors are typically less robust in the face of physical stress than slow-response detectors.        d) Fast-response detectors typically require greater calibration and suffer greater hysteresis than slow-response detectors, and consequently accumulate noise signal faster over their lifetimes.        
But even if the detectors used in the coincidence method were to have instantaneous response times, ambiguity would still remains about whether a coincidence signal was caused by one particle or by more than one particle (an accidental coincidence). This is because a basic feature of the coincidence method is that the particle is not “accounted for” between the physical volumes occupied by the two or more detectors: it was extrapolated to have existed in that space. This is a basic limitation of the coincidence method, and a factor that is in stark opposition to the operation of the novel means described herein. The novel means described herein can be described, in contrast, as a continuous method of particle path detection that cannot be “fooled” by conventional accidental coincidences.
It is a further object of this invention to energetically discriminate penetrating charged particles. There are several methods in the prior art to achieve this, discussed below.
The first prior art method for energy discrimination of penetrating charged particles, as utilized in patent above U.S. Pat. No. 3,049,619 A, is to discriminate the opening angle of a Cherenkov light-cone in a dielectric medium in order to determine the energy (momentum) of the incident charged particle. This is achieved by virtue of the fact that the opening angle of a Cherenkov light-cone is directly proportional to the velocity of the penetrating charged particle. This prior art method is unrelated to the novel means described herein and is included for context and as an attempt at completeness.
The second, more pervasive, method for energy discrimination of penetrating charged particles is what can be called the magnetic deflection method, whereby a charged particle passes through a produced magnetic field, and a departure from a straight-line path is exhibited by the particle, which follows the magnetic-geodesic curve dictated by its magnetic rigidity (i.e. a convolution of its charge and momentum) and the strength of the magnetic field applied. There exist only two ways of measuring the curvature of this magnetic-geodesic path in the prior art, namely the aforementioned coincidence method and the aforementioned photographic method, which have their concomitant disadvantages which have been already enumerated.
The novel means described herein uses a unique directional discrimination capability in the service of a modified magnetic deflection method to achieve energy discrimination that relies on neither the coincidence method nor the photographic method.
A topically similar (but substantially different) device for detecting the presence, but not the directional or energetic discrimination, of penetrating charged particles is described in U.S. Pat. No. 3,984,332 A. In that patent a fiber optic (which is, essentially, a one-dimensionally elongated dielectric surrounded by a specular reflector) is used as a Cherenkov-producing medium and transmission line, all-in-one. Discussed therein is the feature of fiber optics that only photons traveling with an angle sufficiently parallel the longitudinal axis of the fiber optic experience complete internal reflection and thus transmission. Fiber optics can transmit light from the part of a Cherenkov light-cone produced therein only if it lies within the critical angle of the fiber optic, as necessitated by the limitations of the fiber optic transmission. Therefore, it could be stated, though it is not done so in U.S. Pat. No. 3,984,332 A, that only those penetrating charged particles that impinge the fiber optic at an angle (in relation to the fiber's longitudinal axis) that corresponds to the sum of opening angle of the Cherenkov cone (typically about 45 degrees)±the acceptance angle of the fiber optic will definitely have the potential to produce some photons that transmit. This does not translate, however, into anything besides a directional limitation (either the photons can transmit or they can't) on the purely binary signal that travels down the fiber optic, identifying the existence of some particle at some time. This feature is a relic of fiber optics, and seems to be viewed by the author of U.S. Pat. No. 3,984,332 A as a limitation, only.
Further, regarding U.S. Pat. No. 3,984,332 A, no directional or energetic discrimination is described as derived from the interaction between the fiber optic and a penetrating charged particle. Further, no discrimination of the number of photons produced is described. Rather, the timing of the light flashes is used in a conventional coincidence method, which suffers from the all of the same disadvantages described above.